Passengers were taken to hospitals. Most were treated for minor injuries from bruises to broken bones and released, but seven were hospitalized.

The Neal's Bus Service charter bus was just east of Princeton, Ill., about 10 a.m. when the driver lost control of the vehicle, said Illinois Police Master Sgt. David Spahn.

The bus rolled at least once before landing on its right side in the median, Spahn said.

Employees at the Chicago bus company declined to comment on the accident or say from where the bus had originated.

Spahn said the passengers were traveling to the President Casino.

He said he did not know whether the passengers were part of an organized trip.

Two passengers, Gerald Boyd, 56, and Ella Abram, 50, both of the Chicago area, were taken to Perry Memorial Hospital in Princeton, then transferred to OSF St. Francis Hospital in Peoria, said St. Francis nursing supervisor Michelle Sheppard.

Both patients were in surgery Sunday evening. Boyd was listed in critical condition, and Abram was in serious condition, Sheppard said.

Five other passengers were being kept overnight for observation in Princeton-area hospitals.

The remaining passengers were treated at Perry Memorial Hospital in Princeton, St. Margaret Hospital in Spring Valley, Ill., and Illinois Valley Community Hospital in Peru, Ill., and released.

According to Carol Howes, a nurse supervisor, the four passengers who were being held for observation Sunday night at Perry were Robert McBride, 44; Tara Lockett, 24; Verdean Turnipseed, 59; and Sharon Borom, 45.

All were from the Chicago area, but their addresses were unknown. A 24-year-old woman was being kept overnight at Illinois Valley for observation.

Nursing supervisors at the three hospitals said another Neal's bus arrived about 5 p.m. to pick up passengers who had been treated at the hospitals to take them back to Chicago.

Freezing rain caused icy conditions and numerous car accidents along I-80 in central Illinois on Sunday, Spahn said. None of the other accidents resulted in serious injuries, he said.

Lisa Miller, a nursing supervisor at St. Margaret, said many passengers were shaken up after the accident.